A flexible printed circuit board for COF (Chip On Film) is an important component connected with the display panel in a thin film display device. As illustrated in FIG. 1, a flexible printed circuit board comprises a base layer A, a conductive layer B, a solder resist layer (SR layer) C and an IC component D; surfaces of all film layers is designed to be planar, with the conductive layer B disposed between the base layer A and the SR layer. When a module is subjected to an anti-vibration test, a vibration test and transportation, a display panel may be easily vibrated as a gap may exist between the display panel and a housing, thus leading to deformation of the flexible printed circuit board. With such a configuration, the flexible printed circuit board is not effectively buffered and protected when being twisted and deformed by an external force, which will easily lead to breakage of the conductive layer of the flexible printed circuit board and abnormity 1 in input signal of panel, thereby making the possibility of defects high.
In a conventional flexible display device, a planar flexible printed circuit board is generally used. When being used, the flexible display device is often bent and affected by external force (such as tension and pressure) due to its speciality and functionality. A planar flexible printed circuit board can not effectively buffer the external force. Moreover, the flexible display device after being repeatedly bend can easily cause defects, which will affect the quality and life time of the flexible display device.